How does the radiation pattern of a horizontally polarized antenna vary with increasing height above ground?

Ground reflection causes interference patterns that form elevation lobes in an antenna's radiation pattern. As a horizontally polarized antenna is raised higher above the ground (measured in wavelengths), the lowest elevation lobe is pressed closer to the horizon, meaning the takeoff angle decreases. This lower takeoff angle is highly desirable for long-distance (DX) communications, as the signal travels further before reflecting off the ionosphere. Conversely, lowering the antenna increases the takeoff angle, which is better for short-range NVIS communication. Students often mistakenly guess that the takeoff angle increases as the antenna gets higher, or they confuse elevation angles with horizontal beamwidth. Height primarily affects the vertical radiation pattern (takeoff angle), not the horizontal beamwidth.